Network device with selectable trap definitions

ABSTRACT

A network device with selectable traps that improves network management by enabling a system manager or administrator to select between multiple trap definitions. The network device includes a memory that stores a management database including a plurality of trap definitions and a programmable parameter for selecting any one of the trap definitions. The network device further includes management processing logic that executes a management agent that issues traps according a selected one of the trap definitions depending upon the programmable parameter. In the embodiment described herein, the management database includes the standard Ethernet™ Repeater MIB implemented according to RFC 1516 including a first trap definition and the Ethernet™ Hub MIB by Novell including a second trap definition. The management agent issues traps according to either one of the trap definitions depending upon the programmable parameter.

CROSS REFERENCE TO RELATED APPLICATIONS

The present application is based on U.S. Provisional Application SerialNo. 60/050,501 entitled "Dual Speed Stackable Repeater" filed Jun. 23,1997, which is hereby incorporated herein by reference in its entirety.

FIELD OF THE INVENTION

The present invention relates generally to networks for communication,and more particularly to a network device with selectable trapdefinitions.

DESCRIPTION OF THE RELATED ART

Networks serve the purpose of connecting many different electronicdevices such as computers, telecommunications devices, printers, fileservers etc., so that expensive computing assets may be shared amongmany users. Such computing assets include, but are not limited to, dataand software including programs, files, local and global directories,and databases, and hardware including computers, printers, facsimilemachines, copiers, mass storage media, etc., and any combinationthereof.

Various communication protocols and standards for networks have beendeveloped to standardize the way in which data packets are transmittedacross the data exchange media of the network. For example, Ethernet™,Token Ring™, Fiber Optic Inter-Repeater Link (FOIRL) and FiberDistributed Data Interface (FDDI) are some of the commonly known networkmedia standards. Also, each standard has its own baseband transmissionrate achievable on an applicable physical medium. Ethernet™ is ashared-media network architecture defined in the Institute of Electricaland Electronics Engineers (IEEE) 802.3 standard, and is currently themost widely used architecture for local-area networks (LANs). Ethernet™uses both bus and star topologies. The 10Base-T is a physical layerstandard based on the IEEE 802.3k specification, which is a baseband802.3-based Ethernet™ network that operates up to 10 Mbps (megabits persecond), and is configured in a star topology.

Another Ethernet™ standard has emerged, referred to as Fast Ethernet™ or100Base-T Ethernet™, which includes implementations capable of 100 Mbpstransmissions speeds and is defined in IEEE 802.3u. 100Base-T coversthree media types, which includes 100Base-T4 using four pairs ofcategory 3, 4 or 5 unshielded twisted-pair (UTP) wire, and anothertwisted-wire pair scheme referred to as 100Base-TX using two pairs ofcategory 5 UTP or shielded twisted-pair (STP) wire. Also, a 100Base-FXscheme is defined for use with fiber optic cables. It is noted that thepresent disclosure and invention is not limited to any particularcommunications protocol, communication speed, or standard, and may beapplied to other protocols and mediums. For example, fiber optic andCopper Distributed Data Interface (CDDI) systems are also contemplated.

In a star configuration, several nodes or computers are connectedtogether through a common hub, which is otherwise referred to as arepeater in Ethernet™ topologies. A repeater is a hardware device thatgenerally functions at the physical layer of the Open SystemsInterconnection (OSI) Reference Model to provide a common terminationpoint for multiple nodes. In particular, a repeater receives data fromone node and re-transmits the data to other nodes attached to therepeater. Repeaters usually accommodate a plurality of nodes, such as 4,8, 12 or more nodes, and some repeaters include connectors for linkingto other repeaters. Each node in the network is typically a computer ofsome type, such as a personal computer (PC), Macintosh, minicomputer,mainframe, or the like, where the computer generally includes a networkinterface card (NIC) for interfacing the node to the repeater to enablenetworking capabilities. A node may also be a passive device that doesnot transmit, such as a printer. In the present disclosure, each node isassociated with a network device or data terminal equipment (DTE), whereeach node generally refers to any source and/or destination of dataconnected to any network system, such as a LAN or the like.

Presently, there is a trend in network technology towardsinternetworking or enterprise networking, that is, interconnectingnetworks of different baseband transmission rates to achieve evengreater shared access across a larger number of network stations. Acurrent approach to attaining this objective is to use a 2-port bridgedevice capable of filtering data packets between different networksegments or domains by making simple forward/don't forward decisions oneach data packet it receives from any of the segments to which it isconnected. As is understood in the art, these segments may be providedwith a structured wiring architecture such that a repeater (or,synonymously, a hub) or a multi-station access unit (MAU) provides acentral connection point for wiring the network stations disposed inthat domain.

In a conventional configuration, one of the ports of the hub for adomain with one baseband transmission rate is connected to one port ofthe 2-port bridge device, whereas a second hub for a second domain withthe same or a different baseband transmission rate is connected to theother bridge port. As can be readily appreciated by those skilled in theart, at least three separate devices must be interconnected, managed,maintained and serviced in order to provide the conventionalinternetworking solution. Several disadvantages of this arrangement arereadily apparent, including less reliability, expensive maintenance, andsub-optimal usage of form-factor.

Accordingly, it should be appreciated that there has arisen a need foran internetworking system that can operate with segments of differentbaseband transmission rates in a single integrated device. A device thatis capable of switch functions at a higher baseband rate is relativelyexpensive. Also, if several slower speed devices are connected to asingle high speed device, such as a server, much of the high speedswitch capability is wasted, resulting in an inefficient design. It isdesired to provide a cost effective and efficient network for enablingcommunication among data devices operating at different communicationrates. It is further desired to improve effective management of thenetwork.

SUMMARY OF THE INVENTION

A network device with selectable traps according to the presentinvention improves network management by enabling a system manager oradministrator to select among multiple trap definitions. The networkdevice includes a memory that stores a management database including aplurality of trap definitions and a programmable parameter for selectingany one of the trap definitions. The network device further includesmanagement processing logic that executes a management agent that issuestraps according a selected one of the plurality of trap definitionsdepending upon the programmable parameter. The management database mayinclude a first management database including a first set of trapdefinitions, a second management database including a second set of trapdefinitions, where the parameter is programmed to select between thefirst and second sets of trap definitions. The management agent issuestraps according to either one of the first and second sets of trapdefinitions depending upon the programmable parameter.

The management databases may be implemented according to a ManagementInformation Base (MIB) pursuant to the Internet Engineering Task Force(IETN) Simple Network Management Protocol (SNMP). For example, a firstMIB is preferably the standard Ethernet™ Repeater MIB implementedaccording to RFC (request for comments) 1516, and a second MIB ispreferably the Ethernet™ Hub MIB by Novell. Both of these MIBs includesimilar traps, such as health state, group change and reset, that areissued under the same circumstances. However, the management agentprovides different information when issuing the trap depending upon theselected definition. In this manner, if a management application is usedthat is compatible with RFC 1516, then it is desired to use the firstMIB to issue traps compatible with RFC 1516. Alternatively, if amanagement application is used that is compatible with Novell'sEthernet™ Hub MIB, such as Novell's ManageWise™, then it is desired touse the second MIB to issue traps compatible with Novell's Ethernet™ HubMIB. In this manner, the network device is programmable to supporteither trap type and definition.

The programmable parameter preferably corresponds to an object of aprivate or enterprise specific management database used by themanagement agent to determine which types of traps to issue. Theparameter preferably has a default, such as according to RFC 1516. Also,the parameter is preferably stored in nonvolatile memory so that itremains unchanged during power cycles.

The network device is typically part of a network system and includes aninterface for coupling to a management unit. The management unitprograms the parameter and receives traps via the interface. Theinterface may be any network port of the network device for in-bandmanagement. Alternatively, interface may comprise a serial port forout-of-band management. The network device may comprise a multiple portrepeater device, for example, which executes a management agentcompatible with SNMP. The management unit may execute a managementconsole according to or otherwise compatible with SNMP. In this manner,the management console programs the parameter by sending an SNMP requestto the management agent. The management agent programs the parameter andthen issues traps according to the selected trap definition.

Accordingly, it should be appreciated that a system according to thepresent invention improves management by allowing selection of any oneof a plurality of trap definitions.

BRIEF DESCRIPTION OF THE DRAWINGS

A better understanding of the present invention can be obtained when thefollowing detailed description of the preferred embodiment is consideredin conjunction with the following drawings, in which:

FIG. 1A is a simplified block diagram of a network system including aplurality of network devices implemented according to the presentinvention coupled together in a managed stack configuration;

FIG. 1B is a simplified diagram illustrating several nodes, such ascomputer systems or the like, coupled to the network system of FIG. 1A;

FIG. 2 is a flowchart diagram illustrating exemplary scenarios oftransmitting information in a network arrangement provided in accordancewith the teachings of the present invention;

FIG. 3 is a perspective diagram of the network system of FIG. 1Aillustrating exemplary physical connections of a managed stackconfiguration;

FIG. 4 is a system level block diagram of a managing repeater showingthe backplane board and the daughter board;

FIG. 5 is a more detailed exemplary block diagram of a managing baseboard and the backplane expansion interface board of the managingrepeater of FIG. 1A;

FIG. 6 is a more detailed exemplary block diagram of a daughter board ofthe managing repeater of FIG. 1A;

FIG. 7 is a more detailed exemplary block diagram of a manageable baseboard and a slave backplane board of a manageable repeater of FIG. 1A;

FIG. 8 is a more detailed exemplary block diagram of an unmanageddaughter board of a manageable repeater of FIG. 1A;

FIG. 9 is a more detailed and exemplary block diagram of the WMIC ofFIGS. 5-8;

FIG. 10 is a more detailed block diagram of the management engine ofFIG. 6;

FIG. 11 is a block diagram of an exemplary management engine controllerused in the management engine of FIG. 10;

FIG. 12 is a front view of the physical housing of the managing repeaterof FIG. 1A;

FIG. 13 is a block diagram of the managing repeater of FIG. 1Aillustrating a management agent, a management bus, management databasesand other management functions; and

FIG. 14 is a block diagram of the adaptive repeater interface controllermodules shown in FIGS. 5-8.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Referring now to FIG. 1A, a simplified block diagram is shown of anetwork system 100 including a plurality of network devices implementedaccording to the present invention coupled together in a managed stackconfiguration. The network devices are multiple port repeaters 102, 104,106, 108 and 110 physically and logically coupled together across acommon backplane bus 112. Each of the repeaters 102-110 includes a firstsegment 102a, 104a, 106a, 108a and 110a, respectively, and a secondsegment 102b, 104b, 106b, 108b and 110b, respectively. The firstsegments 102a-110a operate at a first transmission rate and the secondsegments 102b-110b operate at a second transmission rate.

In the embodiment shown, the first segments 102a-110a are Ethernet™ 10Mbps repeater segments operating according the Ethernet™ 10Base-Tstandard . The 10 Mbps repeater function is optionally 10Base-Tcompliant supporting up to four repeater hops. The second segments102b-110b are Ethernet™ 100 Mbps repeater segments each operatingaccording to the Ethernet™ 100Base-TX standard. Each of the segments102b-110b are coupled together via the common backplane bus 112. Asdescribed further below, the backplane bus 112 includes a repeaterportion 112a (FIG. 13) and a management portion 112b. In the embodimentshown, the repeater portion 112a of the common backplane bus 112includes a Fast Ethernet™ component that operates at a transmission rateof 100 Mbps, where the 100 Mbps repeater function is preferablyaccording to 100Base-TX Class I. The present invention, however, is notlimited to any particular protocol or transmission rate or class andcontemplates a plurality of different protocols and transmission rates.For example, the slower segments 102a-110a may operate at 100 Mbps whilethe faster segments 102b-110b and the repeater portion 112a of thebackplane bus 112 operate at a transmission rate of one gigabit persecond (Gbps). Further, a configuration with more than two segments perunit is contemplated and the backplane may be disposed between anycorresponding segments.

Segmentation is the process of isolating or coupling an individualsegment from/to a common collision domain. Each of the switch devices102c-110c may be separately disabled, so that any one or more of thesegments 102a-110a may be separated from its corresponding segment102b-110b, respectively, and thus separated from the repeater portion112a of the backplane bus 112. Also, each of the repeaters 102-110 maybe separately disconnected from the repeater portion 112a of the commonbackplane bus 112 and thus from the common collision domain.

Each of the repeaters 102-110 further includes a two-port learningbridge or switch device 102c, 104c, 106c, 108c and 110c, respectively.Each switch device 102c-110c is coupled to a corresponding segment102a-110a, respectively, and to a corresponding segment 102b-110b,respectively, within the repeaters 102-110, respectively, as shown inFIG. 1A. The segments 102b-110b are incorporated into the same repeateror collision domain via the repeater portion 112a of the backplane bus112. Each of the segments 102a-110a are in separate collision domains,which thereby reduces the number of collisions on each of the segments102a-110a and the segments 102b-110b including the repeater portion112a. Nonetheless, as further described below, the switch devices102c-110c enable communication and data transfer between each of thesegments 102a-110a and the corresponding segments 102b-110b,respectively. In this manner, a network device or node coupled to anyone of the segments 102a-110a may communicate with any device on anyother segment of any of the repeaters 102, 104, 106, 108 and 110. Thestacked configuration with multiple segments is transparent to eachnetwork device coupled to any port of any of the repeaters 102-110, sothe each network device appears to be part of the same logical LAN.

Any one of the repeaters 102-110 is operable as a standalone unit. Anytwo of the manageable repeaters 104-110 may be coupled together with aone-to-one physical backplane connection in an unmanaged stackconfiguration, resulting in one repeater domain with one repeater hop.For example, the repeaters 104 and 106 may be coupled together in anunmanaged stack configuration. The respective segments 104a and 106a areinterconnected via the switch devices 104c and 106c and the segments104b and 106b via the backplane bus 112, where the switch devices 104c,106c act as store and forward devices with modified MAC (media accesscontrol) address filtering.

In the embodiment shown, the network system 100 is a managed stackconfiguration, in which one of the repeaters, such as the repeater 102,is a managing unit and the remaining repeaters 104-110 are manageableunits. All of the ports of the repeaters 102-110 have access to amanagement agent 1302 (FIG. 13) implemented within the managing repeater102 regardless of connection speed as long as they have access to themanagement portion 112b of the common backplane bus 112. The ports ofthe segment 102b always have access to the management agent 1302 of themanaging repeater 102. However, if any of the switch devices 102c-110cis disabled, the corresponding segments 102a-110a, respectively, losetheir access to the management agent 1302. Of course, when any of themanageable repeaters 104-110 is disconnected from the repeater portion112a, the ports of the disconnected manageable repeater lose access tothe management agent 1302.

As described further below, the managing repeater 102 is assigned asingle Media Access Control (MAC) address, otherwise called a hardwareor physical address, which is an industry-wide unique address identifierincluding six (6) bytes. The management agent 1302, which manages theentire managed stack configuration, is accessible via the using singleMAC address. Also, at the higher level network layer, a single localInternet Protocol (IP) address (32-bit for version 4, 128-bit forversion 6) or network address may be used for all segments of the stackas part of a single logical LAN rather than having to assign separateaddresses for each of the segments or for each different collisiondomain. This results in a less expensive implementation by eliminationof at least one MAC device, yet provides a more convenient LANconfiguration. In this manner, devices coupled to any of the ports ofeach of the repeaters 102-110 are part of the same logical domain orLAN. Thus, in the managed stack configuration using the backplane bus112, the network devices coupled to any of the repeaters 102-110 arepart or the same logical domain or LAN via the common backplane bus 112.

In the managed stack configuration shown in FIG. 1A, a networkmanagement station or platform 116 is coupled to any one of the ports ofthe repeaters 102-110 for "in-band" management. The managing repeater102 also includes a serial port 114 that couples to and interfaces withthe management platform 116 for various purposes including "out-of-band"management. The management platform 116 is able to manage the entirenetwork system 100 via the management agent 1302 of the managingrepeater 102. The management platform 116 may be as simple as aManagement Information Base (MIB) browser for accessing MIB objects ofone or more MIBs supported within the repeaters 102-110. The managementplatform 116 may be more sophisticated, such as a management consolerunning an SNMP (Simple Network Management Protocol) network managementapplication using SNMP over IP or over IPX (Internetwork PacketExchange). The SNMP management application submits management requests,such as enable/disable ports, backup port assignments, trap tableentries, statistics, etc. to a SNMP management agent 1302 within amanagement module within the managing repeater 102. The repeater 102also preferably supports a VT100 terminal emulation interface via theserial port 114 for supporting basic management and configurationfunctions. For SNMP out-of-band management using the management platform116 via the serial port 114, a Serial Line Internet Protocol (SLIP) orPoint-to-Point Protocol (PPP) is established for exchanging packetsbetween the managing repeater 102 and the management platform 116 viathe serial interface. The serial port 114 also enables remote terminalemulation or management using a modem.

FIG. 1B is an exemplary diagram illustrating several nodes NODE 1, NODE2, NODE 3, NODE 4, NODE 5 and NODE 6, such as computer systems or thelike, coupled to the network system 100. In particular, nodes NODE 1 andNODE 2 are each coupled to the segment 102b of the repeater 102, NODE 3is coupled to the segment 104b of the repeater 104, NODE 4 and NODE 5are each coupled to the segment 102a of repeater 102 and NODE 6 iscoupled to the segment 104a of repeater 104. Communication between eachof the nodes occurs using Ethernet™ packets, each including source anddestination MAC addresses. Packets may be unicast, multicast orbroadcast. For broadcast packets, the "destination" address indicatesthat the packet should be broadcast to every other device or to multipledevices. Unicast packets include a destination MAC address identifying aparticular node or network device for which the packet is intended. Apacket transmitted by NODE 1 to NODE 3 is received and then repeated bythe segment 102b to NODE 2 and to the repeater portion 112a of thebackplane bus 112. The packet is received by segment 104b of therepeater 104, which repeats the packet to NODE 3. NODE 3 may respondwith a packet of its own, which is received and repeated by the segment104b to the repeater portion 112a of the backplane bus 112. The packetis received by the segment 102b and repeated to both nodes NODE 1 andNODE 2, so that NODE 1 receives the response packet. NODE 2 may ignoreor drop the packet if it is not addressed to NODE 2.

In the embodiment shown, the switch devices 102c-110c learn the MACaddresses of devices coupled to ports that are connected to the firstsegments 102a-110a, respectively. The switch devices 102c-110c, however,do not learn the MAC addresses of devices coupled to ports that areconnected the second segments 102b-110b, respectively. In alternativeembodiments, the switch devices 102c-110c are configured to learn theMAC addresses of devices coupled to both the first and second segments102a-110a and 102b-110b. In the embodiment shown, the switch device 102clearns the MAC addresses for NODE 4 and NODE 5, and the switch device104c learns the MAC address for NODE 6. The switch devices 102c-110cforward packets from a respective second segment 102b-110b to arespective first segment 102a-110a only if the packet includes adestination address that matches a learned MAC address, and thus only ifidentifying a device on the respective first segment 102a-110a. Theswitch devices 102c-110c forward packets from a respective first segment102a-110a to a respective second segment 102b-110b only if the packetincludes a destination address that does not match any of its learnedMAC addresses, and thus only if not identifying any device on therespective first segment 102a-110a.

For example, if the packet transmitted by NODE 1 included a destinationaddress that identified the MAC address of NODE 5, then the switchdevice 102c forwards the packet to the segment 102a, which repeats thepacket to nodes NODE 4 and NODE 5. The same packet is also received bythe switch device 104c, but ignored and not sent to the segment 104asince the switch device 104c does not learn nodes of a separate segment.If a packet sent by NODE 3 included a destination address for NODE 1,then both of the switch devices 102c and 104c filter the packet, so thatthe packet is not repeated on the first segments 102a and 104a. Localtraffic on the first segments 102a-110a is filtered by the respectiveswitch devices 102c-110c. Thus, a packet sent by NODE 4 with adestination MAC address identifying NODE 5 is filtered by the switchdevice 102c and not asserted on the corresponding second segment 102b.Thus, local first segment traffic is not repeated on the collisiondomain of the second segment, thereby reducing traffic and collisions onthe second segments 102b-110b and the repeater portion 112a of thebackplane bus 112.

Network devices or nodes on separate first segments may communicate.Thus, a packet sent by NODE 4 with a destination MAC address identifyingNODE 6 is transmitted by the switch device 102c to the second segment102b since the destination address was not known by the switch device102c. The second segment 102b repeats the packet to the segment 104b ofthe repeater 104 via the repeater portion 112a of the backplane bus 112.The switch device 104c recognizes the learned address for NODE 6, andsends the packet to NODE 6 via the first segment 104a.

Referring now to FIG. 2, a flowchart diagram is shown illustratingexemplary scenarios of transmitting information in a network arrangementprovided in accordance with the teachings of the present invention. FIG.2 illustrates transmitting information from a network station D1 to areceiving network station D2 within a multi-segmented network having amanaged stack such as, for example, the managed stack network system 100shown in FIGS. 1A and 1B. As can be appreciated by those skilled in theart, the network stations D1 and D2 may be disposed in two differentdomains operating on different baseband signaling specifications. Thus,it should be understood that based on different combinations severalscenarios for communication signal flow may occur. For example, D1 maybe coupled to a slower segment, such as, for example, the first segment102a of the multiple port repeater 102 shown in FIG. 1A, whereas D2 maybe coupled to a faster segment, such as for example, the second segment108b of the multiple port repeater 108. On the other hand, D1 may becoupled to a faster segment while D2 is coupled to a slower segment.Moreover, D1 and D2 may be attached to segments of the same unit or tosegments of different units in the stack. Accordingly, it should beappreciated that the flow diagram provided in FIG. 2 illustrates anexemplary methodology for signal flow in the various alternativescenarios rather than a sequential flow of a series of decision steps.

A network transmission is initiated from D1 and it is presumed that D2is the intended receiver. A first transmission scenario 120 illustratesthe situation when both D1 and D2 are connected to the same repeaterunit and are disposed on the same network segment. In this case, thetransmission is made from D1 to D2 as shown at step 121 without bridgingvia a switching device, which transmission may be made according to asuitable communications standard that is used for the network segment.In scenario 130, both D1 and D2 are attached to the same unit but aredisposed on two different segments. That is, if D1 is on a fast segment,D2 is on the slow segment and vice versa. In this case the integratedswitching functionality of the repeater unit, such as performed by anyone of the switching devices 102c-110c, is utilized as shown at step 131to effectuate the data transmission from D1 to D2 at step 132.

Continuing to refer to FIG. 2, scenarios 140, 150 and 160 describesituations wherein D1 and D2 are connected to different units of thenetwork system 100. When both D1 and D2 are disposed on a fast segmentas in scenario 140, the transmitting unit places the data on therepeater portion 112a of the backplane bus 112 at step 141 which isreceived by the receiving unit to which D2 is attached. D2 receives thetransmitted information at step 132 without any need for intermediatebridging.

When D1 and D2 are disposed on different segments of different units asillustrated by scenario 150, the location for bridging would be based onwhether the sending network station D1 is on a slow segment or fastsegment, as is indicated at decision step 151. If D1 is on the slowsegment, then the information is bridged to the fast segment disposed inthe unit to which D1 is attached at step 152, and the information thenplaced on the repeater portion 112a of the backplane bus 112 at step153. The information is then received by D2 which is on the fast segmentat step 164. On the other hand, if D1 is on the fast segment asdetermined at step 151, the information is placed on the repeaterportion 112a of the backplane bus 112 directly at step 154 and receivedand bridged at the receiving unit at step 155, where the informationsubsequently transmitted to the slow segment to D2 at step 164.

When D1 and D2 are on separate slow segments, the information needs tobe bridged in the transmitting unit at step 161, and transmitted via therepeater portion 112a of the backplane bus 112 at step 162. Once theinformation is received at the receiving unit, it is bridged onto theslow segment (step 163) and repeated to the destination station D2 atstep 164.

It is appreciated by those skilled in the art that if a separate slowbackplane, comparable to the fast backplane, is provided interconnectingthe slow segments of the units, then arbitration capability may beincorporated to direct traffic from a slow D1 to a slow D2 either viathe bridge-backplane-bridge path or via the direct slow backplane.However, providing additional cabling for the stackable slow backplaneand arbitration capability may increase system complexity andinefficiency associated therewith.

Referring now to FIG. 3, a perspective diagram of the network system 100is shown illustrating the physical connections of a managed stackconfiguration. The managing repeater 102 includes a backplane expansioninterface board 302 that further includes four backplane connectors 304.Each of the manageable repeaters 104-110 includes a single backplaneconnector 304. Each one of four cables 306, having appropriate andcompatible conductors and connectors, is connected between acorresponding one of the four connectors 304 of the managing repeater102 and the connector 304 of one of the manageable repeaters 104-110. Inthis manner, the backplane bus 112 is logically a single bus but isphysically implemented in a star configuration, where each of themanageable repeaters 104-110 are connected directly to the managingrepeater 102, allowing for up to five stacked units in the embodimentshown. Preferably, each of the connectors 304 are female 68-pin SCSI(Small Computer System Interface) II D-type connectors. Each of thecables 306 are preferably 68-conductor shielded flat ribbon cables withmale 68-pin SCSI II D-type connectors. Of course, any suitable cable andconnector configuration may be used. Also, although only five repeatersare shown in the stacked configuration, it is understood that thepresent invention is not limited to any particular number of units inthe stack. The repeater portion 112a and the management portion 112b ofthe backplane bus 112 are both included in each of the connectors 304and cables 306.

The backplane board 302 is connected via a suitable backplane boardconnector 310 to a managing base board 312 within the managing repeater102. The managing base board 312 preferably incorporates 12auto-negotiating 10/100 Ethernet™ ports as further described below. Themanaging base board 312 further includes a daughter board connector 314for receiving and connecting a daughter board 316, which also preferablyincorporates another 12 auto-negotiating 10/100 Ethernet™ ports for atotal of 24 ports. Each of the manageable repeaters 104-110 includesimilar logic and are implemented in a similar manner as the managingrepeater 102, except that the manageable repeaters 104-110 do notinclude the sophisticated management agent.

FIG. 4 is a system level block diagram of the managing repeater 102showing the backplane board 302 and the daughter board 316 coupled tothe managing base board 312. Also shown is a Smart Uplink Module (SUM)402 and a power supply 404 coupled to the managing base board 312. Theoptional SUM 402 implements an uplink port that plugs into the baseboard 312 to enable extension of the topology of the 100 Mbps Class Ifast segment beyond the standard 200 meter diameter restriction. Theconnection is preferably accomplished using a 50-pin connector, and theuplink connection is either a 100Base-TX or 100Base-FX port, althoughother types of port connections are possible and contemplated.

FIG. 5 is a more detailed block diagram of the managing base board 312and the backplane expansion interface board 302 of the managing repeater102. The managing base board 312 includes 12 Ethernet™ portsindividually labeled PORT 1-PORT 12. Each of the ports PORT 1-PORT 12includes a port connector 502 such as an RJ-45 socket for receiving acompatible RJ-45 plug with a twisted-pair cable for coupling to anetwork device. Each port connector 502 is coupled to a physical layercircuit 504 containing an integrated PHY device and associated magneticmodule (isolation transformer and common mode coil, etc.) for isolationand electromagnetic interference (EMI) reduction. Each physical layercircuit 504 is preferably an ICS 1890 dual speed device or the likewhich supports both 10 and 100 Mbps CSMA/CD (Carrier Sense MultipleAccess with Collision Detection) Ethernet™ applications. Each physicallayer circuit 504 also includes on-chip auto-negotiation functions thatdetermine the capabilities of the network device coupled thereto andadjusts operation for the highest performance common operating mode. Thephysical layer circuit 504 preferably supports the IEEE 802.3u MediaIndependent Interface (MII) for connection to MACs or repeaters, andalso implements a 10 Mbps serial bit stream interface. Each of threeAdaptive Repeater Interface Controller (ARIC) modules 506 is coupled toand controls four of the physical layer circuits 504. The physical layercircuits 504 are also configured and controlled via an Media IndependentInterface (MII) management data serial bus (MDIO) bus 508, which isfurther coupled to a management interface controller (MIC) 510, furtherdescribed below.

Each of the ARIC modules 506 is coupled to a 10 Mbps repeater module 512and a 100 Mbps repeater module 514 via appropriate transmit (TX) andreceive (RX) BUS signals to provide a connection between the physicallayer circuits 504 and either of the 10 or 100 Mbps repeater modules512, 514. Each ARIC module 506 monitors link status and connection speedfrom its physical layer circuits 504 and routes packet data to theappropriate repeater module. At 100 Mbps, the TX BUS and the RX BUSestablish a 13-port MII link to enable communication between the couplednetwork device and the 100 Mbps repeater module 514. The MII linkhandles 13 ports, one each for the ports PORT 1-PORT 12 and anadditional uplink port 503 for the optional SUM 402 so that the optionalSUM 402 is coupled via a 100 Mbps MII link to the repeater module 514.At 10 Mbps, a serial bit stream interface via corresponding PseudoAttachment Unit Interface (PAUI) ports are used to enable communicationbetween each ARIC module 506 the 10 Mbps repeater module 512.

Each ARIC module 506 is preferably a Field Programmable Gate Array(FPGA) design that translates 10 Mbps Non-Return-To-Zero (NRZ) data froma physical layer circuit 504 to Manchester data for PAUI ports, andvice-versa. Each ARIC module 506 multiplexes the RX BUS to eliminate theneed for external tri-state buffers, and demultiplexes the 100 Mbps TXBUS from the repeater module 514 to four of the physical layer circuits504. Each ARIC module 506 provides a connection between four of thephysical layer circuits 504 and the respective four ports of each of therepeater modules 512, 514. 10 Mbps network devices are coupled to the 10Mbps repeater segment of the 10 Mbps repeater module 512 and 100 Mbpsnetwork devices are coupled to the 100 Mbps repeater segment of the 100Mbps repeater module 514 regardless of which of the ports PORT 1-PORT 12that the network device is connected to. The repeater module 512 ispreferably an IMR2 by Advanced Micro Devices, Inc. (AMD). The repeatermodule 514 is preferably the BCM5012 by Broadcom Corporation.

In general, an MII link includes a bundle of four transmit data signalsTXD<3:0>, a bundle of four receive data signals RXD<3:0>, a transmitclock signal TX₋₋ CLK, a receive clock signal RX₋₋ CLK, a transmitenable signal TX₋₋ EN, a transmit coding error signal TX₋₋ ER, a receivedata valid signal RX₋₋ DV, a receive error signal RX₋₋ ER, a repeatercollision signal COL and a carrier sense signal CRS. In the embodimentshown, each physical layer circuit 504 auto-negotiates with a couplednetwork node device via a corresponding port connector 502, asserts arespective SPEED signal to indicate either 10 Mbps or 100 Mbpstransmission rate and then operates at the indicated transmission rate.Each physical layer circuit 504 includes an MII-type interface to oneARIC module 506 for both 10 and 100 Mbps operation. For the 100 Mbpscase, the corresponding SPEED signal indicates 100 Mbps and the MIIinterface operates in a normal manner. For the 10 Mbps case, thecorresponding SPEED signal indicates 10 Mbps and the MII interface isoperated in a serial bit stream mode in the NRZ format using only theRXD<0> and TXD<0> signals for data. Also, the RX₋₋ CLK and TX₋₋ CLKsignals are both operated at 10 MHz for the 10 Mbps case. Each ARICmodule 506 includes four MII-type ports for both 10 and 100 Mbpsoperation, where each couples to an MII interface of a corresponding oneof the physical layer circuits 504.

In the embodiment shown, the repeater module 514 handles 13 MII ports,but includes only a single MII data port with a single set of RXD<3:0>and TXD<3:0> data pins, one TX₋₋ ER pin, one RX₋₋ DV pin, one RX₋₋ ER,one RX₋₋ CLK pin and one TX₋₋ CLK pin. The repeater module 514 includes13 CRS pins, 13 COL pins, 13 LINK pins, 13 TX₋₋ EN pins and 13 portenable PORTEN pins and interfaces one port at a time. Each ARIC module506 includes a single MII data port with a single set of RXD<3:0> andTXD<3:0> data pins, which are coupled to the respective pins of the MIIport of the repeater module 514 via the RX BUS and the TX BUS,respectively. Each ARIC module 506 further includes four LINK pins andfour CRS pins, which are coupled to four of the 12 LINK and CRS pins ofthe repeater module 514. Each ARIC module 506 includes four PORTEN inputpins which are coupled to a corresponding four of the 12 PORTEN signalsof the repeater module 514.

In the embodiment shown, the repeater module 512 includes 12 PseudoAttachment Unit Interface (PAUI) ports that operate using Manchesterencoded data. Each PAUI port includes a pseudo AUI data output (PDO)signal, a pseudo AUI receive data input (PDI) signal and a pseudo AUIcollision input (PCI) signal. Each ARIC module 506 includes four PDO1-4,PDI1-4 and PCI1-4 pins that carry the respective PDO1-4, PDI1-4 andPCI1-4 signals that are provided to corresponding PDO1-4, PDI1-4 andPCI1-4 pins of the repeater module 512 for interfacing a respective fourof the ports of the repeater 102.

FIG. 14 is a block diagram of each of the ARIC modules 506. Within eachARIC module 506, a clock divider circuit 1402 receives and synchronizesa system reset signal RST and provides a synchronized reset signalRESET. The repeaters 102-110 each include clock circuitry (not shown)for generating a 20 MHz clock signal CLK20 and a 25 MHz clock signalCLK25. The CLK20 signal of the repeater 102 is provided to the clockdivider circuit 1402, which generates a 10 MHz clock signal CLK10 and a5 MHz clock signal CLK5 from the CLK20 signal. Each of the physicallayer circuits 504 auto-negotiates the speed of a device or node coupledto a corresponding port and generates a corresponding SPEED signalindicating the transmission rate of the coupled device and a link statussignal LSTA. A speed and link detector block 1404 receives four SPEEDsignals SPEED1-4 and four link status signals LSTA1-4 from fourassociated physical layer circuits 504 and generates four corresponding10 Mbps slow link signals SLNK1-4, four corresponding 100 Mbps fast linksignals FLNK1-4 and four corresponding link signals LINK1-4. The LINK1-4signals are coupled to a corresponding four of the 12 LINK pins of therepeater module 514. The LINK1-4 signals each correspond to acorresponding one of either the SLNK1-4 signals or the FLNK1-4 signalsdepending upon the corresponding SPEED signal. The SLNK1-4 and FLNK1-4signals are used for purposes of multiplexing the receive paths anddemultiplexing the transmit paths, which is further described below.

Each of four port carrier sense signals PCRS1-4 from respective physicallayer circuits 504 are logically ANDed together within each ARIC module506 with a corresponding one of the FLNK1-4 signals with respective2-input AND logic gates 1406, which provide a corresponding fourrepeater carrier sense signals RCRS 1-4. In this manner, each carriersense signal PCRS from the corresponding physical layer circuit 504 isprovided to the repeater module 514 in the form of a corresponding RCRSsignal only if the port is 100 Mbps. The corresponding link signal LINKis provided to the repeater module 514 regardless of port speed. Thephysical layer circuits 504 are configured to clock transmit data with aclocking signal REF₋₋ IN. The CLK25 signal from the clock circuitry isprovided to the input of a buffer 1418, which provides the REF₋₋ INsignal at its output. The REF₋₋ IN signal minimizes delay skew betweenthe transmit clock CLK25 and the transmit data signals TXD<3:0>.

The TXD<3:0> and TX₋₋ EN signals of the TX BUS are provided to thecorresponding TXD<3:0> and TX₋₋ EN pins of the ARIC module 506, whichare coupled to an input of a 1-to-4 demultiplexor (DEMUX) 1408. The fourTX₋₋ EN signals and corresponding FLNK1-4 signals are used to controlthe select inputs of the DEMUX 1408 to select one of four transmit paths1408a, 1408b, 1408c and 1408d when the corresponding TX₋₋ EN signal isasserted. The transmit paths 1408a-d are provided to respective inputsof four 2-to-1 MUXs 1410, 1412, 1414 and 1416, respectively, which haverespective outputs that provide TXD<3:0> and TX₋₋ EN signals,collectively shown as the TXPORT1-4 signals, respectively, to theassociated four physical layer circuits 504 handled by the particularARIC module 506. The select inputs of the MUXs 1410-1416 are controlledby the respective SLNK1-4 signals to select the 100 Mbps transmissionpaths 1408a-d or corresponding 10 Mbps transmission paths, describedbelow.

The RXD<3:0>, RX₋₋ DV and RX₋₋ CLK signals of four of physical layercircuits 504, collectively referred to as RXPORT1-4 signals, areprovided to four respective inputs of a 4-to-1 MUX 1420, which providesa selected set of RXPORT signals, called RXPORT100, to the inputs of aset of tri-state buffers 1422. Note that four RX₋₋ DV1-4 and RX₋₋ CLK1-4signals are provided, one for each of the four ports. Four port enablesignals PRTEN1-4 of the corresponding PRTEN pins of the ARIC module 506are provided to the select inputs of the MUX 1420 to select one of thefour ports. The PRTEN1-4 signals are effectively ORed together so thatany one asserted enables the buffers 1422 to drive the selected portsignals RXPORT100 as the RXD<3:0>, RX₋₋ DV and RX₋₋ CLK signals of theRX BUS to the repeater module 514.

Since the repeater module 512 transmits data on PDO1-4 signalssimultaneously, only one 10 Mbps Manchester decoder 1424 is required forfour ports. The Manchester decoder 1424 receives the CLK20 signal andfour PDO1-4 signals for four ports, monitors for signal transitions ofthe combined PDO1-4 signals and aligns data bit-symbols to convertManchester format to NRZ format. Each bit symbol is split into twohalves with the first half containing the logical complement of the bitvalue and the second half containing the true bit value. The true bitvalues are provided to the input of a 7×2 (7 bits deep by 2 bits wide)configured TX first-in, first-out buffers (FIFOs) 1426, where each ofseven data bits includes a valid flag bit. It is noted that only one TXFIFO 1426 is provided for the four ports. When the Manchester decoder1424 detects data being transmitted by the repeater module 512 for anyof the four ports, it indicates to the TX FIFO 1426 to receive data. TheTX FIFO 1426 sets the corresponding valid flags for each valid bit, andthe Manchester decoder 1424 signals the last valid data bit.

When the physical layer devices 504 operate in 10 Mbps mode, they clockthe transmit data with their TX₋₋ CLK signal. Therefore, four 10 Mbps TXserializers 1428 are provided. Each of the four 10 Mbps TX serializers1428 receives the output data of the TX FIFOs 1426 and a correspondingone of the four transmit clock signals TX₋₋ CLK1-4 from respectivephysical layer devices 504. The output of each of the four TXserializers 1428 is provided to the other input of a respective one ofthe MUXs 1410-1416 for the respective ports. When the TX serializer 1428detects valid data in the TX FIFO 1426 and a corresponding PDO1-4 signalis active, it provides corresponding TXD<3:0> data and TX₋₋ EN signalsof TXPORT1-4 to the corresponding physical layer circuit 504 via thecorresponding one of the MUXs 1410-1416. The TX₋₋ EN signals aregenerated by a corresponding TX serializer 1428 based on the valid flagbits, where the TX₋₋ EN signals remain asserted for each valid data bit.The TX serializer 1428 cycles through the TX FIFO 1426 and clocks datato the corresponding physical layer device 504 for each data that hasits valid flag bit set. The respective 10 MHz TX₋₋ CLK signals providedfrom the physical layer devices 504 are used to clock the data intorespective physical layer circuits 504. The TX serializer 1428 completesthe transmission process when it detects an invalid flag, where it thendeasserts a respective TX₋₋ EN signal.

One bit of data is written to the TX FIFO 1426 for every two cycles ofthe CLK20 signal. One bit of data is written by a TX serializer 1428 forevery clock cycle of the corresponding TX₋₋ CLK1-4 signal provided bythe corresponding physical layer circuit 504. Ideally, if the CLK20 andTX₋₋ CLK1-4 signals were synchronized and did not vary with respect toeach other, only one data bit would be needed in the TX FIFO 1426.However, the CLK20 and TX₋₋ CLK1-4 signals are not necessarily in phaseand further may have frequencies that vary with respect to each other inthe embodiment shown. A 10 Mbps data rate represents a bit rate ofapproximately 100 nanoseconds (ns). Ethernet packets have a maximum of1,518 bytes or 12,144 bits. Given the variation between the two clocksignals, the Manchester decoder 1424 and the TX serializer 1428 may varyby 1-2 bits with respect to each other for a given packet. The TXserializer 1428 waits for at least 3-4 bits written to the TX FIFO 1426by the Manchester decoder 1424 before pulling data from the TX FIFO 1426to ensure that data is not lost. The TX FIFO 1426, therefore, is sevendata bits deep to ensure that data is not lost if either side is fasteror slower by 1-2 bits than the other side.

The four sets of RXPORT1-4 signals are provided to respective inputs ofa 4-to -1 MUX 1430, which provides a selected set of RXPORT signals,shown as RXPORT10, to the input of a 6×2 (6 bits deep by 2 bits wide)configured RX FIFO 1432. The 6×2 configuration includes a valid flag bitfor each data bit in a similar manner as described above for the TX FIFO1426. The select input of the MUX 1430 is controlled by the SLNK andPCRS signals to select the active port. As soon as a respective RX₋₋DV1-4 signal is detected by the RX FIFO 1432 from the MUX 1430, the RXFIFO 1432 writes the RXD<0> data using the falling edge of thecorresponding 10 MHz RX₋₋ CLK to ensure proper setup and hold times. TheRX FIFO 1432 sets a corresponding valid flag bit for each valid data bitin a similar manner as described above for the TX FIFO 1426. Once thefirst data bit is written into the RX FIFO 1432, it sets the valid flagbit to notify a 10 Mbps Manchester encoder 1434 to receive and encodethe data and to provide encoded data to the repeater module 512 on arespective one of the four PDI1-4 signals. The Manchester encoder 1434performs the reverse process as the Manchester decoder 1424 to convertNRZ formatted data to Manchester encoded data for the repeater module512.

The Manchester encoder 1434 cycles through the RX FIFO 1432 until itdetects an invalid flag indicating the end of the packet. If any of therespective four physical layer devices 504 detects a collision, itasserts a respective one of the COL1-4 signals provided to theManchester encoder 1434, which respondingly drives a 10 MHz clock signalon a respective one of the four PCI1-4 signals. In the event of acollision, the RX FIFO 1432 is held in reset until the PCRS1-4 carriersense and RX₋₋ DV1-4 signals are deasserted. The Manchester encoder 1434ignores data in the RX FIFO 1432 in the event of collision and continuesto send a data bit "1" to the repeater module 512 until the respectivePCRS1-4 carrier sense signal is deasserted. The repeater module 512sends an alternating jam pattern (10101 . . . ) until its receiving portgoes idle. Thus, valid encoded data is present on corresponding PDI1-4signals only for those ports that have a corresponding valid LINK1-4signal and PCRS1-4 carrier sense signal asserted.

In a similar manner as described above for the TX FIFO 1426, the 10 MHzRX₋₋ CLK signals provided through the MUX 1430 are not in phase with theCLK20 signal, and the frequencies may vary significantly with respect toeach other. This is especially true since each of the RX₋₋ CLK signalsare passed through the logic of the MUX 1430. Thus, the MUX 1430 and theManchester encoder 1434 may vary by up to 2-3 bits for a full Ethernetpacket. When the Manchester encoder 1434 detects first valid data in theRX FIFO 1432, it waits at least one bit-time or approximately 100 ns andthen begins to encode the NRZ formatted data in the RX FIFO 1432 toManchester format, and writes the data to the DI1-4 signals. The delayis between 3-4 bit times or 300-400 ns before encoding is completed. TheRX FIFO 1432 includes 6 bits to ensure that data is not lost in theevent either side is faster or slower by 2-3 bits with respect to eachother for a given packet.

The repeater module 512 includes an internal memory 505 for storingstatistics of each port via the port connectors 502 operating at 10Mbps. In particular, the repeater module 512 tracks, updates andmaintains each of several statistics for each port coupled to a 10 Mbpsdevice and stores the statistics in the memory 505. The repeater module514 is coupled via a management bus 550, described below, to a memory519 for storing statistics of each port via the port connectors 502coupled to and operating at 100 Mbps. The repeater module 514 tracks,updates and maintains each of several statistics for each port coupledto a 100 Mbps device and stores the statistics in the memory 519. Thetypes of statistics stored include the number of readable frames,readable octets, collisions, short events, runt frames, very longevents, frames too long, late events, frame check sequence (FCS) errors,frame alignment errors, data rate mismatches, total errors, last sourceaddress, source address changes, auto-partitions, dropped events, codingerrors, isolates, etc. Of course, this list is not intended to beexhaustive as many other types of statistics may be tracked and storedas desired. Also, as further described below, similar statistics aretracked at the repeater level and unit level. Although each repeatermodule 512, 514 includes a separate memory device, it is understood thata single memory device could be used instead.

A switch device module 516 corresponds to each of the switching devices102c-110c, and is preferably the Macronix MX98201 10/100 self-learningbridge. The switch device module 516 includes a 100 Mbps port coupled toan MII MAC port of a 100 Mbps repeater module 514 and a 10 Mbps portcoupled to a Reversible-AUI (RAUI) port of the 10 Mbps repeater module512 through an ENDEC (Encoder/Decoder). The switch device module 516 ispreferably coupled to a 256-Kbyte packet buffer memory 518 for both 10and 100 packet data. The packet buffer memory 518 is split between 100and 10 Mbps segments at a default of 15:1 ratio, but is programmable toa 7:1 ratio. Broadcast and multicast packets are forwarded in bothdirections but may be blocked using MIB objects. The switch devicemodule 516 is further coupled to a CAM (Content-Addressable Memory)device 520 via a CAM controller 522. The CAM device 520 is used to storea MAC address table with up to 511 or 1023 MAC address entries and toperform address lookup. In an unmanaged stack configuration, CAM entriesare automatically flushed or cleared when the CAM device 520 becomesfull when another new address is received. In a managed stackconfiguration, the management agent 1302 has the option to flush the CAMdevice 520 when full or not. The CAM controller 522 is preferably anFPGA design that interfaces the switch device module 516 to the CAMdevice 520.

The CAM controller 522 captures source and destination MAC addressesfrom a packet data bus of the switch device module 516. The sourceaddresses (SA) are used for learning and purging purposes and thedestination addresses (DA) are used for filtering purposes. Preferably,only SAs from the 10 Mbps segment are learned; SAs from the 100 Mbpssegment are not learned. In particular, a SA of a packet from the 10Mbps segment invokes a learning task for storing the SA if not alreadystored, and an SA of a packet from the 100 Mbps segment invokes apurging task. For example, if the SA from a 100 Mbps packet matches anentry in the CAM device 520, the entry is purged since it is no longeron the 10 Mbps segment. If a DA from a packet from the 10 Mbps segmentmatches an entry in the CAM device 520, the packet is local and notforwarded to the 100 Mbps segment. Otherwise, the CAM controller 522indicates to the switch device module 516 to forward the packet to the100 Mbps segment. If a DA from a 100 Mbps packet matches an entry in theCAM device 520, the switch device module 516 forwards the packet to the10 Mbps segment. Otherwise, the 100 Mbps packet is not forwarded to the10 Mbps segment.

The management bus 550, which includes control, address and datasignals, is coupled to the 10 and 100 Mbps repeater modules 512, 514,the switch device module 516, the CAM controller 522 and the MIC 510.The management bus 550 is also coupled to the four backplane connectors304 via the daughter board expansion connector 314, the backplane boardconnector 310 and sets of transceivers 545, 546 and 547, respectively,for coupling to the management portion 112b of the backplane bus 112.The MIC 510 is further coupled to an Electrically Erasable ProgrammableROM (EEPROM) 524 and to a Non-Volatile RAM (NVRAM) 526, and interfacesto the daughter board connector 314. The MIC 510 generally providesmanagement access to the various resources and modules of the repeater102 via the management bus 550. A COM port connector 530 includingRS-232 connections to the daughter board connector 314 provides theserial port 114 for basic out-of-band management and configurationfunctions. The serial port 114 is used for several purposes, includingpre-boot Power On Self Test (POST) messages, boot messages, VT100emulated terminal management via direct connection, SNMP and Telnetmanagement via SLIP, firmware update via XMODEM transfer, etc. Theserial port 114 may thus be used for "out-of-band" management purposesfor interfacing a management console via the management platform 116.Management is typically performed "in-band", however, via any one of theports of the repeaters 102-110.

A 100M local arbiter 515 is coupled between the repeater module 514 andthe daughter board connector 314 for arbitrating access between the 100Mbps segments of the repeater modules 514 and 614. A 10M local arbiter517 is coupled between the repeater module 512 and the daughter boardconnector 314 for arbitrating access between 10 Mbps segments of therepeater modules 512 and 612. A 100M global arbiter 521 located on thebackplane board 302 is coupled via the backplane connector 310 and toeach of the expansion connectors 304 for arbitrating all of the 100 Mbpssegments of the repeaters 102-110.

The TX BUS is provided for transmitting information and data from therepeater module 514 to any one or more of the ARICs 506 and to the SUM402, if provided, and thus to any network devices coupled to the portsPORT 1-PORT 12 operating at 100 Mbps. The RX BUS receives informationand data from any one or more of the ARICs 506, the SUM 402 if present,and also from any other repeaters coupled via the repeater portion 112aof the backplane bus 112, where the information and data is provided tothe repeater module 514. The RX BUS is coupled to a 100 Mbps expansionbus 540 through transceiver 542. The expansion bus 540 is coupledthrough the daughter board connector 314 and the backplane boardconnector 310 to four sets of transceivers 544. Each of the transceivers544 is coupled to a corresponding one of the backplane connectors 304for coupling to the repeater portion 112a of the backplane bus 112. Asdescribed previously, the backplane connectors 304 are coupled to otherrepeaters, such as the repeaters 104-110, via corresponding cables 306forming the physical embodiment of the repeater portion 112a of thebackplane bus 112. In this manner, the repeater module 514 is coupled tothe backplane bus 112 and is part of a single 100 Mbps collision domainbetween the repeaters 102-110.

FIG. 6 is a more detailed block diagram of the daughter board 316 of themanaging repeater 102. The daughter board 316 also includes twelve portconnectors 602 coupled to PHY devices 604, which are further coupled tothree ARICs 606 in a similar manner as described above for the managingbase board 312. The ARICs 606 are preferably implemented in a similarmanner as the ARICs 506, described above. The twelve ports are alsolabeled PORT 1-PORT 12 on the daughter board 316, although these portsare remapped as ports PORT 13-PORT 24 on the repeater. The PHY devices604 are further coupled to another MIC 610 via another MDC/MDIO bus 608,and the ARICs 606 are each coupled to another 10 Mbps repeater module612 and another 100 Mbps repeater module 614 on the daughter board 316.The repeater modules 612, 614 are configured in a similar manner as therepeater modules 512, 514, respectively. The repeater module 612 tracks10 Mbps statistics of the ports via the port connectors 602 whenoperating at 10 Mbps and includes an internal memory 605 for storing the10 Mbps statistics in a similar manner as described above for therepeater module 512 and the memory 505. Also, the repeater module 614tracks 100 Mbps statistics of the ports via port connectors 602 whenoperating at 100 Mbps. The repeater module 614 is coupled to a memory619 via a management bus 650 for storing the 100 Mbps statistics in asimilar manner as described above for the repeater module 514 and thememory 519. Although each repeater module 612, 614 includes a separatememory device, it is understood that a single memory device could beused instead. Further, a single memory device may be used rather thanall of the memories 505, 605, 519 and 619 as desired.

The MIC 610 is coupled to another EEPROM 620 and to the 10 and 100 Mbpsrepeater modules 612, 614 via the management bus 650 on the daughterboard 316 in a similar manner as previously described. The managementbus 650 is an extension of the management bus 550 on the managing baseboard 312 through the daughter board connectors. The management buses550, 650, 750 and 850, described below, and the management portion ofthe backplane bus 112b are all part of and extensions of a generalmanagement bus 1300 (FIG. 13) of the network system 100. The managementbus 1300 is also extended via the MICs 510, 610 and similar MICs 710 and810, described below. It is noted that the daughter board 316 does notinclude another switch device module 516. Instead, the 10 and 100repeater modules 612, 614 are coupled to the switch device module 516 onthe managing base board 312 via the repeater modules 512, 514 on thebase board 312 and the daughter board connector 314. The Reverse MII(RMII) MAC port of the 100 Mbps repeater module 614 is coupled to a 100Mbps MAC device in the management engine 616. The management engine 616includes an RS-232 port for interfacing RS-232 signals of the serialport 114 via daughter board connector 314.

The daughter board 316 includes another TX BUS for enabling the repeatermodule 614 to transmit information and data to the ARICs 606 and thus tothe ports PORT 13-PORT 24. The daughter board 316 further includesanother RX BUS coupled between the repeater module 614, the ARICs 606and a 100 Mbps expansion bus 640 via transceiver 642. The RX BUS of thedaughter board 316 is thus an extension of the RX BUS of the base board312 of the managing repeater 102. The expansion bus 640 is coupled tothe expansion bus 540 via the daughter board connector 314. In thismanner, data and information transmitted to the repeater 102 via thenetwork portion 112a of the backplane bus 112 is provided to therepeater module 614 in a similar manner as described above for the RXBUS of the repeater module 514.

FIG. 7 is a more detailed exemplary block diagram of the "manageable"base board and the "slave" backplane board of a manageable repeater,such as any one of the repeaters 104-110. The base board of a manageablebase board is similar to that of a managing base board excluding theNVRAM 526. The slave backplane board of a manageable repeater includesonly one backplane connector 304. The manageable base board includes asimilar RX BUS that is expanded via the slave backplane board to theexpansion connector 304 via transceivers 744 in a similar manner asdescribed above for the managing base board shown in FIG. 5 viatransceivers 544. Thus, the RX BUS of a manageable repeater isextendable to other repeaters via the repeater portion 112a of thebackplane bus 112. Also, the management bus control, address and datasignals of the management portion 112b of the backplane bus 112 arecoupled to the local MICs 710, 810 of the manageable base board and an"unmanaged" daughter board via transceivers 745, 746 and 747,respectively, and a management bus 750. The management bus 750 isconsidered an extension of the management bus 1300 of the managingrepeater 102 in a stacked configuration via the management portion 112bof the backplane bus 112. A 100M local arbiter 715 is coupled betweenthe repeater module 714 and the daughter board connector for arbitratingaccess between 100 Mbps ports of the repeater modules 714 and 814.

The repeater modules 712, 714 are configured in a similar manner as therepeater modules 512, 514, respectively. The repeater module 712 tracks10 Mbps statistics of associated ports via port connectors 702 whenoperating at 10 Mbps and includes an internal memory 705 for storing the10 Mbps statistics in a similar manner as described above for therepeater module 512 and the memory 505. Also, the repeater module 714tracks 100 Mbps statistics of the ports via the port connectors 702 whenoperating at 100 Mbps. The repeater module 714 is coupled to a memory719 via the management bus 750 for storing the 100 Mbps statistics in asimilar manner as described above for the repeater module 514 and thememory 519.

FIG. 8 is a more detailed exemplary block diagram of the unmanageddaughter board of a manageable repeater, such as any one of therepeaters 104-110. An unmanaged daughter board is similar to a managingone except excluding the management engine 616 and correspondingmanagement functions. The unmanaged daughter board also includes an RXBUS expanded to the RX BUS of the manageable base board of eachmanageable repeater via another daughter board connector via transceiver842. In this manner, the 100 Mbps segments of the unmanaged daughterboards of the repeaters 104-110 are coupled to each other and to the 100Mbps segment of the managing repeater 102 in the same collision domainvia the repeater portion 112a of the backplane bus 112. The control,address and data signals of the management portion 112b of the backplanebus 112 are coupled to the MIC 810 via a daughter board connector and acorresponding extension management bus 850 in a similar manner asdescribed previously for the managing repeater 102.

The repeater modules 812, 814 are configured in a similar manner as therepeater modules 512, 514, respectively. The repeater module 812 tracks10 Mbps statistics of associated ports via port connectors 802 whenoperating at 10 Mbps and includes an internal memory 805 for storing the10 Mbps statistics in a similar manner as described above for therepeater module 512 and the memory 505. Also, the repeater module 814tracks 100 Mbps statistics of the ports via port connectors 802 whenoperating at 100 Mbps. The repeater module 814 is coupled to a memory819 via the management bus 850 for storing the 100 Mbps statistics in asimilar manner as described above for the repeater module 514 and thememory 519.

Each of the manageable units 104-110 includes an external MASTER/TARGETswitch to reverse the sense of backplane arbitration. In a managed stackconfiguration including a managing unit, such as the repeater 102, theMASTER/TARGET switch of each of the manageable repeaters 104-110 is setto TARGET. Two manageable units, such as repeaters 104 and 106, may becoupled together with a single cable 306 coupling the backplaneconnectors 304 forming an unmanaged stack configuration. TheMASTER/TARGET switch of one of the manageable units in the unmanagedstack configuration is set to MASTER and the other is set to TARGET.Setting the MASTER/TARGET switch to MASTER effectively enables the 100Marbiter 715 of one of the manageable units, whereas setting theMASTER/TARGET switch to TARGET disables the 100M arbiter 715 of theother unit. Thus, only one of the manageable units performs backplanearbitration in the unmanaged stack configuration.

FIG. 9 is a more detailed block diagram of both of the MICs 510 and 610,where each of the MICs 510, 610, 710 and 810 are similar to each otherfor both the managing and manageable repeaters. The MIC 510 is brieflydescribed herein and the description is similarly applicable to the MICs610, 710 and 810. The MIC 510 includes a Serial Management InterfaceController (SMIC) 902, which provides control of base and daughter boardPHY devices through MII SMIC to PHY device registers. The SMIC 902 alsoprovides for non-volatile storage of up to eight register values per PHYdevice in serial EEPROM with an additional eight register valuesavailable for broadcasts. The MIC 510 further includes status andcontrol logic for Light Emitting Diodes (LEDs) provided on each of therepeaters 102-110. For example, the MIC 510 includes 10/100 switch LEDstatus conditioning logic 904, 10M repeater LED interface control logic906, timing circuitry 908 and LED control logic 910. Many other logic,circuits and components are provided on the MICs 510, 610.

FIG. 10 is a more detailed block diagram of the management engine 616 ofthe repeater 102. The primary module on the management engine 616 is aprocessor 1002, which is preferably an 80386 EX central processing unit(CPU) by Intel. The management engine 616 preferably includes a MACidentification (ID) memory device 1004 that stores the MAC address forthe managing repeater 102. The single MAC address is used by themanagement agent 1302 (FIG. 13) in a managed stack configuration as thephysical address for the MAC device for in-band managementcommunications. The management engine 616 is coupled to the managementbus 1300 of the network system 100 via the management buses 650 and 550and the management portion 112b of the backplane bus 112 as previouslydescribed. In this manner, the management engine 616 provides managementfunctions for all of the repeaters 102-110 of the network system 100.

Although not shown in FIG. 10, the management engine 616 includes aManagement Engine Controller (MEC) 1100. FIG. 11 is a block diagram ofthe MEC 1100. Many other logic, circuits and components are provided onthe management engine 616 and the MEC 1100 but they are not described asthey are not necessary for a full understanding of the presentinvention.

FIG. 12 is a front view of the face plate of the physical housing of amanaging repeater, such as the repeater 102. The 24 port connectors 502for each of the ports PORT 1-PORT 24 are shown in two rows of twelve,twelve each for the base and daughter boards previously described. Eachport includes a status LED 1202 above the corresponding port connector.Each of the LEDs 1202 provide LINK status, activity status or whetherthe port is partitioned or disabled. The COM port connector 530 is shownalong with an RJ-45 connector 1204 for the uplink port 503. A POWER LEDindicates whether power supply 404 is providing power to the repeater,and a STATUS LED indicates the general status of the repeater. One ormore failure or fault conditions are indicated by the color (green oryellow) and flash frequency (blinking or not) of the STATUS LED. Furtherdetails are provided in Appendix A.

A 10 COL LED indicates collisions on the 10 Mbps segment and a 100 COLLED indicates collisions on the 100 Mbps segment. A 10/100 SW LEDindicates whether the internal switch device module 516 is enabled ordisabled and also indicates the operation status of the switch devicemodule 516. A 100 BP LED indicates connection to or isolation from acommon 100 Mbps backplane, such as the repeater portion 112a of thebackplane bus 112. A 10MB LED indicates that the mode and status of theports operating at 10 Mbps are displayed by the LEDs 1202 of therespective ports operating at 10 Mbps. In particular, if the 10MB LED ison or green, then the LEDs 1202 display the status of 10 Mbpsconnections. The LEDs 1202 of those ports either not connected or notoperating at 10 Mbps remain off. A 100MB LED indicates that the mode andstatus of the ports operating at 100 Mbps are displayed by the LEDs 1202of the ports operating at 100 Mbps. In particular, if the 100MB LED ison or green, then the LEDs 1202 display the status of 100 Mbpsconnections. An ALT LED indicates an alternating mode, where the 10MBLED and 100MB LED are alternately turned on and off to alternatelyindicate the status of the 10 and 100 Mbps ports.

An ACT LED on the SUM 402 indicates whether link is active and whetherthere is activity on the uplink port 503. A COL LED on the SUM 402indicates collisions on the uplink port 503 or whether the SUM 402 anduplink port 503 are disabled.

Several switches are also provided on the front panel. A push buttonMODE switch is used for display mode to force either the 10, 100 oralternating display modes described above. A 10/100 10 ONLY rotaryswitch is used to switch the first port, PORT 1, into either 10/100 orforce 10 Mbps mode. When set to 10 ONLY, PORT 1 is forced to operateonly at 10 Mbps and when set to 10/100 , PORT 1 allows auto-negotiationto either 10 or 100 Mbps just like the other ports. An MDIX/MDI rotaryswitch configures the port for MDIX or MDI pinouts for switching the TXand RX signals. When set to MDIX, PORT 1 uses the MDIX pinout and may beconnected directly to a NIC. When set to MDI, PORT 1 uses the MDI pinoutso that PORT 1 may be used as a 10 Mbps uplink port. The face plate of amanageable repeater, such as the manageable repeaters 104-110, issimilar to that shown in FIG. 12, except excluding the COM portconnector 530.

Referring now to FIG. 13, a block diagram is shown of the managingrepeater 102 illustrating the management agent 1302, the management bus1300 and management functions. FIG. 13 shows, in simplified form, thefirst segment 102a and the memories 505, 605 of the repeater modules512, 612, the second segment 102b and the memories 519, 619 of therepeater modules 514, 614, and the switch device module 516 coupledbetween the repeater modules 512 and 514. The management agent 1302accesses the 10 and 100 repeater modules 512, 514, 612 and 614 and theircorresponding memories 505, 519, 605 and 619 for purposes of managementand control via the management bus 1300 and the MICs 510, 610. Themanagement agent 1302 further accesses the 10 and 100 repeater modules712, 714 and 812, 814 and their corresponding memories 705, 719, 805 and819 of each of the manageable repeaters 104-110 included in the stackvia the management bus 1300. As described previously, the management bus1300 couples the management buses 550, 650, 750 and 850, the MICs 510,610, 710 and 810, the transceivers 545, 546 and 547 and correspondingtransceivers 745, 746 and 747 and the management portion 112b of thebackplane bus 112. In this manner, the management agent 1302 has accessto all of the segments 102a-110a and 102b-110b of the network system 100via the management bus 1300. Furthermore, the management platform 116 isable to monitor and manage the network system 100 including all nodescoupled thereto, if desired.

The management agent 1302 manages and controls each of the ports of eachof the repeaters 102-110 in the network system 100 in a unified manner.Unified treatment occurs even though each port of any given repeater mayoperate at 10 Mbps when coupled to the first segment and at 100 Mbpswhen coupled to the second segment. This enables an external managingdevice, such as a management console of the management platform 116, tomanage each of the ports in a unified manner regardless of theparticular protocol or transmission rate and regardless of whetherin-band or out-of-band. As further described below, statistics aregathered for each port when operating at either transmission rate. Inresponse to a "unified" statistics request, a unified statistic isprovided that reflects combined operation at both transmission rates.The statistics request may specify transmission rate, in which case themanagement agent 1302 provides statistics specific to the requestedtransmission rate rather than a unified statistic. As further describedbelow, port intrusion detection and/or intrusion prevention is supportedin a unified manner. If an unauthorized node or station attempts totransmit to a port, that port is shut down regardless of the mediastandard or transmission rate of the intruder or of a subsequent networkdevice. Such unified management enables the management unit to manage orcontrol all of the ports of the network system in a unified mannerregardless of transmission rate or media standard.

The management agent 1302 is preferably implemented as firmware storedin memory within the management engine 616, such as a ROM, FLASH ROM,etc., and executed by a local processor, such as the processor 1002. Themanagement agent 1302 accesses, controls and maintains at least one MIB,which is a database containing information about the elements to bemanaged in the network system 100. A MIB is a definition of a structuredcollection of objects representing one or more nodes, devices,resources, etc. of a network to be managed, controller or otherwisemonitored. The objects in a MIB are ordered in a hierarchical treestructure, typically defined with the ASN.1 (Abstract Syntax Notationone) standard, which is a formal language for defining abstract syntaxof application data. Several standardized MIBs are known, includingMIB-I, MIB-II, Host MIB, Bridge MIB, Hub MIB, RMON MIB, among others.Each of the resources or network devices, such as computer systems ornodes, switches, routers, brouters, bridges, repeaters, hubs, etc. in anetwork may have a standard and/or enterprise-specific MIB(s) formanagement purposes.

The repeaters 102-110 and the management agent 1302 support severalMIBs, including the standard Ethernet™ Repeater MIB (M1) 1310implemented according to RFC 1516, the MIB II (M2) 1312 implementedaccording to RFC 1213, the Remote Network Monitoring (RMON) MIB (M3)1314 implemented according to RFC 1757, the EtheMet™ Hub MIB by Novell(M4) 1316 and at least one enterprise specific MIB (M5) 1318, which is aprivate MIB designed specifically for the network system 100. Therepeater 102 and the management agent 1302 may also support otherstandard or non-standard MIBs designed for the network system 100.

Each of the objects in the MIBs M1-M5 is accessed or otherwisereferenced using a corresponding object identifier (OID), whichcomprises a sequence of integers for traversing the successive nodes ofthe tree structure. Each object has a syntax type, which, by the SMI(Structure of Management Information) convention, is the universal classincluding integers, octet string, null, object identifier and sequence.Other allowable data types are defined, including IpAddress, Counter32,Gauge32, TimeTicks, Opaque, Counter64 and Unsigned32. The SMI identifiesthe data types that may be used in a MIB and how resources arerepresented and named in that MIB. There may be multiple instances of anobject. Each object instance also has a value. For example, an object oftype "integer" may have a value of 9. Each object or a set of objectsdefines the status and characteristics of a network resource. A resourcemanager or management console, such as within the management platform116, monitors the status of the resources by reading the values of theobjects and controls the resources by changing the values of the objectsvia a management agent, such as the management agent 1302. Themanagement information includes control, status, statistics, security,identification, etc. and information, such as packet counts, errorcounters, time counters, IpAddresses, etc.

The management platform 116 monitors and manages the network system 100by sending SNMP requests or the like to the management agent 1302 via amanagement interface (I/F) 1320, where the management agent 1302accesses one or more of the MIBs M1-M5 to retrieve or modify MIBobjects, or to otherwise retrieve information associated with MIBobjects. The management I/F 1320 is any one of the ports of therepeaters 102-110 for in-band management or the serial port 114 forout-of-band management. Each SNMP request includes one or more OIDs tothe objects in the MIB of interest. For example, the management platform116 sends a "GET", "GETNEXT" or "SET" operation with a corresponding OIDto the management agent 1302, which accesses one or more of the MIBsM1-M5 and responds by reading or modifying information corresponding toone or more objects identified by the OIDs in the MIBs according to thespecific operation. The GET operation is used to read a valuecorresponding to an object identified by an OID and the GETNEXToperation is used to read a value corresponding to the next object or"leaf" in the MIB tree referenced by a given OID. The SET operation isused to modify a value corresponding to an object identified by an OID.A "TRAP" operation is similar to an interrupt, where if an object or thevalue corresponding to an object changes, the management agent 1302responds by sending a notification to the management platform 116.

Each of the repeater modules 512, 514, 612, 614, 712, 714, 812 and 814of each of the repeaters 102-110 tracks and stores statistics for eachport coupled to that module in corresponding memories 505, 519, 605,619, 705, 719, 805 and 819 as previously described. The managementplatform 116 sends a request including an OID identifying an objectwithin any one of the MIBs M1-M5 to the repeater 102 to requestinformation or statistics corresponding to that object. The managementagent 1302 responds by accessing the memory associated with one or moreof the repeater modules of the repeaters 102-110 and provides therequested information to the management platform 116. Depending upon therequested information and the MIB, the information may be "unified" forboth the 10 and 100 repeater domains or the information may be specificto either. If the information is one or more unified statistics, themanagement agent 1302 typically combines the statistics from the 10 and100 Mbps repeater modules of a repeater unit and provides the combinednumber or unified statistic to the management platform 116. The unifiedstatistic is typically achieved by summing the corresponding valuestogether for a total count for the corresponding statistic. It iscontemplated that values may be combined in other manners, such assubtraction, multiplication, division, etc. Otherwise, the informationis retrieved from a specific repeater module. In this manner, themanagement platform 116 may ask for port information includingstatistics in one of three different ways: 10 only, 100 only or asummation of both.

For example, a VALID FRAME COUNT is a number that is tracked, maintainedor updated and stored by each repeater module 512, 514, 612, 614, 712,714, 812 and 814 identifying the number of frames (or packets) of validframe length that have been received at a given port associated with aparticular repeater module. A given port, however, may be coupled to a10 Mbps device, a 100 Mbps device, or may have been coupled to bothsequentially during operation. The latter case would occur if a 10 Mbpsdevice was coupled to a given port for a period of time and removed, andthen a 100 Mbps device was coupled to that same port for another periodof time. The 10 Mbps repeater module tracks the 10 Mbps statistics ofthe first device and the 100 Mbps repeater module tracks the 100 Mbpsstatistics of the second device for that port. Thus, any given singleport may have statistics for both. One or more of the MIBs of therepeater 102 includes a corresponding object indicating the number ofvalid frames. However, the object may be unified for both the 10 and 100segments or may be specific to either.

The management platform 116 sends a statistics request to the managementagent 1302 that includes an OID identifying the object of a MIB torequest the number of valid frames received by a particular port. If theobject or the MIB is not unified, then the request indicates theparticular repeater of interest, whether the 10 or 100 statistics aredesired and the port number. For example, the request may include adevice parameter indicating the particular repeater module, a rateparameter indicating 10 or 100 and a port parameter indicating any oneof the 24 ports PORT 1-PORT 24. The management agent 1302 responds byretrieving and providing the corresponding VALID FRAME COUNT from thecorresponding repeater module. If, however, the object is unified, thenthe management agent 1302 responds by retrieving the VALID FRAME COUNTfrom both the 10 and 100 repeater modules, combines the two numbers suchas summing the numbers together, and provides the sum to the managementplatform 116.

The MIB 1310 includes a corresponding "rptrMonitorPortReadableFrames"object indicating the number of valid frames for each of the ports. TheOID of the request is, or otherwise corresponds to"rptrMonitorPortReadableFrames" if the MIB 1310 is intended for therequest. If ten (10) valid frames have been received from a 100 Mbpsdevice and if five (5) valid frames have been received by a 10 Mbpsdevice at the same port PORT 2 of the repeater 102, then the memory 505of the repeater 102 stores a value of five (5) and the memory 519 storesa value of ten (10). The management platform 116 sends a request to themanagement agent 1302 that includes an OID identifying therptrMonitorPortReadableFrames object of the MIB 1310 to request thenumber of valid frames received by PORT 2 of the repeater 102. Themanagement agent 1302 responds by retrieving the VALID FRAME COUNTnumber from both of the repeater modules 512 and 514, sums the numberstogether resulting in fifteen (15) valid frames, and provides the sumvalue to the management platform 16.

The MIB 1318 includes an extended port information table having a tableentry corresponding to each statistic for each port defined in thenetwork system 100. An INDEX is defined for each entry including a UNITID parameter identifying the particular repeater 102-110, a RPTR IDparameter identifying either the 10 or 100 repeater module, and a PORTID parameter identifying a particular port. Suppose the UNIT IDs of therepeaters 102-110 are 1-5, respectively, the RPTR ID is "10" for a 10Mbps repeater module and is "100" for a 100 Mbps repeater module and thePORT ID is 1-24 for ports PORT 1-PORT 24, respectively. The MIB 1318also includes an object "n2feExtPortReadableFrames" corresponding to thenumber of valid frames received at a port. The management platform 116sends a request with an OID="n2feExtPortReadableFrames" with parametersUNIT ID, RPTR ID and PORT ID identifying the particular repeater, therepeater domain and the port, respectively. The management agent 1302returns the corresponding statistic number to the management platform116.

For example, if the management platform 116 sends a request with anOID="n2feExtPortReadableFrames" with parameters UNIT ID=1, RPTR ID=100and PORT ID=2 for PORT 2 of the repeater 102, and assuming the sameframe count numbers of 10 and 5 as described above, the management agent1302 returns a value of ten (10) to the management platform 116 for therepeater module 514. If, however, the management platform 116 sends arequest with an OID="n2feExtPortReadableFrames" with parameters UNITID=1, RPTR ID=10 and PORT ID=2 for PORT 2 of the repeater 102, then themanagement agent 1302 returns a value of five (5) to the managementplatform 116 for the repeater module 512.

Table 1 below lists several statistics that are tracked and maintainedat the repeater stack-level for two of the MIBs, M1 1310 and M4 1316:

                  TABLE 1                                                         ______________________________________                                        Repeater Module-Level Statistics by MIB                                       Repeater Module-Level Statistic                                                                MIB M1 1310 MIB M4 1316                                      ______________________________________                                        Total Octets                 .check mark.                                     Total Partitioned Ports                                                                        .check mark.                                                 Transmit Collisions                                                                            .check mark.                                                                              .check mark.                                     Jabbers                      .check mark.                                     ______________________________________                                    

Table 2 below lists several statistics that are tracked and maintainedat the unit (or repeater unit 102-110) level for the MIBs M1 1310, M31314, M4 1316 and M5 1318:

                  TABLE 2                                                         ______________________________________                                        Unit-Level Statistics by MIB                                                  Unit-Level Statistic                                                                       M1 1310  M3 1314  M4 1316                                                                              M5 1318                                 ______________________________________                                        Total Frames .check mark.                                                                           .check mark.    .check mark.                            Total Octets .check mark.                                                                           .check mark.    .check mark.                            Total Errors .check mark.                                                     Up-time                        .check mark.                                   Dropped Events        .check mark.    .check mark.                            Broadcast Packets     .check mark.                                            Multicast Packets     .check mark.                                            FCS and Alignment     .check mark.    .check mark.                            Errors                                                                        Undersized Packets    .check mark.    .check mark.                            Runts                                 .check mark.                            Fragments             .check mark.                                            Collisions            .check mark.    .check mark.                            Oversized Packets     .check mark.    .check mark.                            Jabbers               .check mark.                                            Late Events                           .check mark.                            Very Long Events                      .check mark.                            Data Rate Mismatches                  .check mark.                            Packets 0-64 Octets   .check mark.                                            Packets 65-127 Octets .check mark.                                            Packets 65-127 Octets .check mark.                                            Packets 128-255 Octets                                                                              .check mark.                                            Packets 256-511 Octets                                                                              .check mark.                                            Packets 512-1023 Octets                                                                             .check mark.                                            Packets 1024-1518     .check mark.                                            Octets                                                                        Utilization           .check mark.                                            ______________________________________                                    

Table 3 below lists several statistics that are tracked and maintainedat the port level for the MIBs MI 1310, M3 1314, M5 1318 and for theVT100 emulation by the management platform 116:

                  TABLE 3                                                         ______________________________________                                        Port-Level Statistics by MIB and VT100                                        Port-level Statistic                                                                        M1 1310  M3 1314  M5 1318                                                                              VT100                                  ______________________________________                                        Readable Frames                                                                             .check mark.                                                                           .check mark.                                                                           .check mark.                                                                         .check mark.                           Readable Octets                                                                             .check mark.                                                                           .check mark.                                                                           .check mark.                                                                         .check mark.                           Collisions    .check mark.                                                                           .check mark.                                                                           .check mark.                                                                         .check mark.                           Short Events  .check mark.                                                                           .check mark.                                                                           .check mark.                                                                         .check mark.                           Runt Frames   .check mark.                                                                           .check mark.                                                                           .check mark.                                  Very Long Events                                                                            .check mark.                                                                           .check mark.                                                                           .check mark.                                                                         .check mark.                           Frames Too Long                                                                             .check mark.                                                                           .check mark.                                                                           .check mark.                                                                         .check mark.                           Late Events   .check mark.                                                                           .check mark.                                                                           .check mark.                                  FCS Errors    .check mark.                                                                           .check mark.                                                                           .check mark.                                                                         .check mark.                           Frame Alignment Errors                                                                      .check mark.                                                                           .check mark.                                                                           .check mark.                                                                         .check mark.                           Data Rate Mismatches                                                                        .check mark.                                                                           .check mark.                                                                           .check mark.                                                                         .check mark.                           Total Errors  .check mark.                                                                           .check mark.                                                                           .check mark.                                  Last Source Address                                                                         .check mark.                                                                           .check mark.                                                                           .check mark.                                                                         .check mark.                           Source Address Changes                                                                      .check mark.                                                                           .check mark.                                                                           .check mark.                                                                         .check mark.                           Auto-partitions                                                                             .check mark.                                                                           .check mark.                                                                           .check mark.                                                                         .check mark.                           Dropped Events                  .check mark.                                  Coding Errors (100M bps)        .check mark.                                  Isolates (100M bps)             .check mark.                                  ______________________________________                                    

The management agent 1302 informs the management platform 116 of certainpredetermined events that occur in the network system 100 using SNMPtraps. Traps are analogous to interrupts used by processors in computersystems, and are often used to indicate unusual events or exceptionconditions. Examples of such events include system crash and reboot,reset, starting conditions (coldStart, warmStart), failure of a port orlink (linkDown, linkUp), an overload condition determined by a thresholdparameter being violated, etc., and includes enterprise-specific events(enterpriseSpecific) which indicates the type of trap. The managementagent 1302 is configured or programmed to monitor one or moreparameters, objects, a group of objects, etc., and to take an action inresponse to a change of a parameter, object, condition, etc. Theresponse often includes informing the management platform 116 of theevent by sending an unsolicited notification via the management I/F1320.

Table 4 below summarizes the traps generated by the management agent1302, where the MIB column indicates the MIB or RFC that defines thetraps, the trap column lists the traps by a convenient name, the "RFC1157 Trap Type" column lists the generic trap category of the SNMPspecification contained in RFC 1157 to which the trap belongs, and the"Variable Bindings" column lists additional MIB objects that areincluded in the trap message:

                                      TABLE 4                                     __________________________________________________________________________    Traps Supported by the Management Agent 1302                                  MIB       Trap   RFC1157 Trap Type                                                                        Variable Bindings                                 __________________________________________________________________________    RFC1157   Cold Start                                                                           coldStart(1)                                                                             (none)                                            (SNMP Specification)                                                                    Authentication                                                                       authenticationFailure(4)                                                                 (none)                                                      Failure                                                             RFC1757   Rising Alarm                                                                         enterpriseSpecific(6):                                                                   alarmIndex,                                       (RMON)           rmon.1     alarmVariable,                                                                alarmSampleType,                                                              alarmValue,                                                                   alarmRisingThreshold                                        Falling Alarm                                                                        enterpriseSpecific(6):                                                                   alarmIndex,                                                        rmon.2     alarmVariable,                                                                alarmSampleType,                                                              alarmValue,                                                                   alarmFallingThreshold                             MIB 1 1310                                                                              Health enterpriseSpecific(6):                                                                   rptrOperStatus,                                   (RFC 1516)       snmpDot3RptrMgt.1                                                                        rptrHealthText                                              Group Change                                                                         enterpriseSpecific(6):                                                                   rptrGroupIndex                                                     snmpDot3RptrMgt.2                                                      Reset  enterpriseSpecific(6):                                                                   rptrOperStatus                                                     snmpDot3RptrMgt.3                                            MIB 4 1316                                                                              Health enterpriseSpecific(6):                                                                   rptrBasHealthState,                               (Novell)         nSnmpDot3RptrMgt.1                                                                       rptrBasHealthText,                                                            rptrBasHealthData,                                                            rptrBasID, rptrExtName                                      Group Change                                                                         enterpriseSpecific(6):                                                                   RptrBasGroupMap,                                                   nSnmpDot3RptrMgt.2                                                                       rptrBasID, rptrExtName                                      Reset  enterpriseSpecific(6):                                                                   rptrBasHealthState,                                                nSnmpDot3RptrMgt.3                                                                       rptrBasHealthText,                                                            rptrBasHealthData,                                                            rptrBasID, rptrExtName                            __________________________________________________________________________

As noted in Table 4 above, the MIBs M1 and M4 each include similartraps, where it is desired to use one set or the other but not both.Both of the MIBs M1 and M4 include a "HEALTH" trap, a "GROUP CHANGE"trap and a "RESET" trap, where the specifics of these differ with theparticular MIB. The HEALTH trap is issued when changes occur in arepeater's operational status. A GROUP CHANGE trap is issued when arepeater unit is added to or removed from the network system 100 stack.The RESET trap is issued after completion of a reset condition. TheGROUP CHANGE trap of the MIB M1 1310 provides the unit number whosestatus has changed whereas the MIB M4 1316 provides a 16-bit bitmapshowing which units are currently present in the stack. The conditionsthat cause each of these traps are the same, but the trap contents aredifferent. Therefore, it is desired to use either the M1 or the M4 typetraps but not both.

The MIB M5 1318 is preferably a private or enterprise specific MIB thatincludes the following object definition for programming M1 or M4 typetraps:

    ______________________________________                                                n2feTrapSupport OBJECT-TYPE                                                     SYNTAX  INTEGER                                                               {                                                                             rfc1516-traps-only(1)                                                         novell-traps-only(2)                                                          }                                                                             ACCESS  read-write                                                            STATUS  mandatory                                                             ::= {n2feUnitInfo x}                                                ______________________________________                                    

where "rfc1516" corresponds to the MIB M1 1310 and "novell" correspondsto the MIB M4 1316. The management platform 116 sends an SNMP SETrequest to program the trap support value to (1) to select the MIB M11310 type traps and to (2) to select the MIB M4 1316 type traps. Themanagement agent 1302 receives the request and programs the trap supportvalue corresponding to the object definition within the MIB M5 1318. Themanagement agent 1302 then uses the appropriate trap definitions asdetermined by the trap support value.

A default may be set for the trap support object. For example, the trapsupport object may have a default value of (1) to program the traps tothe MIB M1 1310 type. In this manner, the trap select object isprogrammed to a value of (1) if it is desired that the managementplatform 116 executes a management application compatible with RFC1516type traps. Alternatively, the trap select object is programmed to avalue of (2) if it is desired that the management platform 116 executesa management application, such as Novell's ManageWise™, compatible withNovell's Ethernet™ Hub MIB. In this manner, the management agent 1302 ofthe managing repeater 102 supports either trap type and definition.Also, the trap support value may be stored in the NVRAM 526 if desiredso that the programmed value remains unchanged during power cycles.

The management agent 1302 and the MIB M5 1318 support intrusiondetection to detect unauthorized nodes or stations and intrusionprevention to prevent intruders from transmitting on the network system100 on any of the ports of any of the repeaters 102-110. Intrusion isdetected regardless of the transmission rate of the node or stationcoupled to a port. Within the MIB M5 1318, each port has severalintrusion-related MIB objects or variables, including ann2feINTRUSIONPORTSTATUS object indicating the intrusion status of theport (disable/enable/tripped) and an n2feINTRUSIONPORTMACADDRESS objectprogrammable with an authorized MAC address for that port. Theembodiment shown allows only one authorized MAC address to be programmedper port. Alternative embodiments allow any practicable number ofauthorized MAC addresses to be programmed for each port. If a node orstation transmits a source MAC address that is not equal to theauthorized MAC address, the port is disabled and the management agent1302 generates an SNMP "health state" trap indicating the intruded port.The intrusion-disabled port remains disabled until re-enabled by themanagement platform 116 using SNMP (via a user or network operator). Then2feINTRUSIONPORTSTATUS (intrusion status of each port) and then2feINTRUSIONPORTMACADDRESS (the authorized MAC address) variables arestored in the NVRAM 526. In this manner, when the network system 100 orany particular repeater 102-110 resets due to power interruption orsoftware download, all of the ports previously disabled via theintrusion feature remain disabled during boot phase and after themanagement agent 1302 resumes operation until explicitly enabled by themanagement platform 116.

In the embodiment shown, each of the repeater modules 512, 514, 612,614, 712, 714 and 812, 814 is programmable by the management agent 1302with an authorized MAC address per port. The authorized MAC addressesmay be stored in any convenient manner, such as in the memories 505,605, 705 or 805 of the repeater modules 512, 612, 712 or 812,respectively, and the memories 519, 619, 719 and 819 for the repeatermodules 514, 614, 714 and 814, respectively. As described above, theauthorized MAC addresses are also stored in the NVRAM 526 by themanagement agent 1302. The management agent 1302 also enables any one ormore of the repeater modules for intrusion monitoring. When a port is tobe secured by assigning an authorized MAC address, the management agent1302 preferably programs and enables both of the 10 Mbps and 100 Mbpsrepeater modules associated with that port. For example, to secure PORT3 of the repeater 102, both of the repeater modules 512 and 514 areprogrammed with the same MAC address for PORT 3, and both modules areenabled for port intrusion monitoring. Each repeater module that isenabled for port intrusion monitors the source MAC address of eachpacket received on a secured port. For Ethernet™ packets, the sourceaddress is provided within the first 12 bytes of the packet. Therepeater module then compares the received source address with theassigned MAC address for that port. If the addresses match, the packetis processed as normal. If the addresses do not match, the managementagent 1302 is informed and the port is disabled.

Each of the repeater modules informs the management agent 1302 of anunauthorized intruder by asserting an interrupt on the management bus1300 to the CPU 1002 executing the management agent 1302. Alternatively,the repeater module sets a flag in memory or a register, where the flagis periodically polled by the management agent 1302. In the embodimentshown, the 10 Mbps repeater modules 512, 612, 712 and 812 areconfigurable to automatically disable the intruded port. The managementagent 1302 disables the intruded port of the 100 Mbps repeater modules514, 614, 714 and 814. When the management agent 1302 is informed of anintruded port, the management agent 1302 disables the port for theassociated repeater module for that port. For example, if the repeatermodule 512 detects an intruded port, such as PORT 4, it generates aninterrupt to inform the management agent 1302. The management agent 1302then disables the same port PORT 4 for the repeater module 514.Likewise, if the repeater module 514 detects an intruded port, themanagement agent 1302 disables the same port for the repeater module512.

Based on the foregoing, those skilled in the art now understand andappreciate that the stackable integrated system described herein isoperable with at least two different baseband signaling specificationsthat operate at different transmission rates. Because the systemprovided in accordance with the teachings of the present inventionreduces the total number of components typically used for effectuatingdata transmissions across separate basebands, it provides higherreliability and cost-effectiveness. Because of the reduction in thecomponents and stacked configuration, the system provides a highlydesirable form-factor such that less space is needed for installationand operation.

The stackable integrated system described herein also provides forunified management of all of the ports. A separate set of statistics arekept for each port and for each transmission rate. A management systemresponds to statistics requests by providing statistics for eithertransmission rate or a combination of both in the unified case.Intrusion detection and prevention are supported on any port in aunified manner. Several standard management databases are supported. Themanagement system is programmable to select the traps of any particularnon-standard or standard databases, such as the standard Ethernet™Repeater MIB implemented according to RFC 1516 or the Ethernet™ Hub MIBby Novell. Intrusion detection is supported for any and all ports of allrepeater units in a stack regardless of transmission rate.

Although a preferred embodiment of the present invention has beenillustrated in the accompanying drawings and described in the foregoingDetailed Description, it will be understood that the invention is notlimited to the embodiment disclosed, but is capable of numerousrearrangements, modifications and substitutions without departing fromthe spirit of the invention as set forth and defined by the followingclaims. For example, whereas the functionality of a slow first segment,a fast second segment and a switching device therebetween may all beimplemented in a single substrate integrated circuit solution, therespective functionality may also be partitioned to produce a singleboard-level solution. Also, though in the embodiment shown the switchdevice learns the addresses of devices of one segment, it could beconfigured to learn the MAC addresses of the other segment or of bothsegments. Furthermore, although the presently illustrated exemplaryembodiment of the present invention utilizes Ethernet™ technology, thoseskilled in the art will readily appreciate upon reference hereto thatthe teachings of the present invention may be extended to other LANtechnologies, such as Token Ring™, FOIRL, FDDI and the like.

Also, as has been mentioned earlier, a managed stack according to thepresent invention may be provided with additional backplanes, eitherfast or slow. Nor is it a requirement of the present invention that thestackable fast backplane must match the individual fast segments of thestackable units in the bit transmission rate. It is quite possible toprovide a Gigabit/second type backplane while the so-called fastsegments of the units may operate only at 100 Mbps. The integratedswitching functionality of the devices of the present invention may becoupled with a routing device, giving rise to a "brouter" functionality.It may be appreciated that a simple router or a bridge may also providebridging capability. Moreover, a plurality of integrated hubs may beprovided in accordance with the teachings of the present inventionwherein each such hub comprises multiple segments, each having adifferent baseband capability. These hubs may be disposed in disparatedomains and interconnected in a stackable arrangement via one or morebackplanes. Accordingly, it is envisaged that all these rearrangements,modifications, substitutions and extensions are comprehended within thescope of the present invention which is solely limited by the followingclaims.

What is claimed is:
 1. A network device with selectable traps,comprising:a memory that stores a management database including aplurality of trap definitions and a programmable parameter for selectingany one of said plurality of trap definitions; and management processinglogic coupled to said memory that executes a management agent thatissues traps according to a selected one of said plurality of trapdefinitions depending upon said programmable parameter.
 2. The networkdevice of claim 1, further comprising:said memory storing a firstmanagement database including a first set of trap definitions and asecond management database including a second set of trap definitions;and said management processing logic issuing traps according to one ofsaid first and second sets of trap definitions depending upon saidprogrammable parameter.
 3. The network device of claim 2, wherein saidfirst and second management databases are both management informationbases according to the simple network management protocol.
 4. Thenetwork device of claim 3, wherein said first management database is astandard network device management information base.
 5. The networkdevice of claim 4, wherein said first management database is implementedaccording to RFC
 1516. 6. The network device of claim 2, wherein saidfirst and second sets of trap definitions include a health trapdefinition, a group change definition and a reset definition.
 7. Thenetwork device of claim 1, wherein said programmable parameter is anobject of a unified management database used by said management agent.8. The network device of claim 1, wherein said programmable parameter isprogrammed by default to select one of said plurality of trapdefinitions.
 9. The network device of claim 1, wherein said programmableparameter is stored in nonvolatile memory to maintain selection througha power cycle.
 10. The network device of claim 1, wherein saidmanagement processing logic includes a microprocessor.
 11. A networksystem, comprising:a network device with selectable traps, including:aninterface; a management database including a first set of trapdefinitions, a second set of trap definitions and a programmableparameter for selecting between said first set of trap definitions andsaid second set of trap definitions; and management processing logicthat executes a management agent that accesses said management databaseand that issues traps according to one of said first and second sets oftrap definitions depending upon said programmable parameter; and amanagement unit coupled to said network device interface that programssaid programmable parameter and that receives said traps via saidinterface.
 12. The network system of claim 11, wherein said interface isa serial port.
 13. The network system of claim 11, wherein said networkdevice is a multiple port repeater.
 14. The network system of claim 11,wherein said management unit executes a management console according tothe simple network management protocol (SNMP).
 15. The network system ofclaim 14, wherein said management unit programs said programmableparameter by sending an SNMP request to said management agent via saidinterface.
 16. The network system of claim 11, wherein said managementdatabase includes first and second management information basesimplemented according to the simple network management protocol (SNMP).17. The network system of claim 16, wherein said first managementinformation base is implemented according to RFC
 1516. 18. The networksystem of claim 11, wherein said first and second sets of trapdefinitions include a health trap definition, a group change definitionand a reset definition.
 19. The network system of claim 11, wherein saidprogrammable parameter is an object of a unified management databaseused by said management agent.